large twin advice, P38

[corsha99]

First I will admit that I am a novice when it comes to electric planes. I have a typhoon 3d and a Ultimate Bipe that are electric but small in comparison to my question.

I am designing a sport scale P38 for my "business" that originally is set up to use 31cc ryobis for power. I think I want to go with electric though to simplify the propulsion system and take the risk out of having mismatched thrust, etc. What would be a good starting point for the propulsion? I am leaning towards a geared system to swing the bigger props and to keep the amps down.

P38 will be about 20ish pounds with a span of about 10 ft. Don't remember the wingloading off the top of my head. Max prop diameter is 18". I live in Denver so need a system that can perform at altitude (~5600 ft where I fly)

Thanks for the help,
Cory
gotgasradiocontrol.com

[mpope1]

I have a 90" p-38 powered by twin hacker a50-16s motors(6s lipo's per motor). It weighs about 18 lbs. A 10 ft w.s. would probably be more then 20 lbs. Is it scratch build, or a kit?

[corsha99]

For me it is a scratch build that will eventually become a kit. I know how to keep them very light (balsa, light ply, minimal good ply) but that equals not damage tolerant. My sport aerobatic model weighs in at 11 lbs with a ryobi in the nose. 87" span, 1000 sq in wing.

[Lynxman]

18" is pretty small props for a plane that large. The scale diameter would be ~26".

A couple of Hacker A50 16L on 8S will probably spin an APCE 18x10 prop with great performance on a 20 lbs plane. I haven't tried the combo though.

[corsha99]

It is not a true scale. Wingspan is larger than what it would normally be to help with flyability. Ryobis up here don't like to swing anything bigger than 20" on slow, trainer types. I use 16" on faster models.

Design is such that you can fit up to 20" with a bit of clearance to the center fuse. Guess I need to readdress that when using a different motor.

[Lynxman]

Ok, I see.

[172AMD]

mpope1, What props are you running on those Hacker A50-16s motors? Amps, watts?

Thanks Dave.

[mpope1]

On 5s 17x10, on 6s 16x10. Trying to keep the amps around the mid 60's around 1300 watts per side on 6s. My ultimate goal was to use the apc 15 3/4 x 13 3 bladed but didn't want to spend the extra cash on spinners.

[172AMD]

Thanks mpope1